Experience has shown that a camshaft, being not very rigid, reacts violently to the severe forces imposed by conventional milling cutters now in use to mill cam profiles. Such milling cutters have cutting inserts mounted on the cylindrical periphery of a head which turns on an axis parallel to the camshaft. The cutting inserts move in a circular path at right angles to the axis of rotation of the camshaft, and the full force of each cutting insert is exerted in a direction perpendicular to the camshaft.
In accordance with the present invention, the cutting inserts move in a path forming an angle of less than 90.degree. to the axis of rotation of the camshaft, so that during most of the cut a substantial component of the cutting force is transmitted along the axis of the camshaft and absorbed by the headstock or tailstock of the lathe.
More specifically, the cutting inserts are mounted on a cone-shaped milling head the axis of rotation of which intersects the axis of rotation of the camshaft at an acute angle. The cutting inserts take a shaving cut, beginning at a point on one side edge of the cam and ending in a line across the full width of the cam. Because of the acute angle orientation of the milling head, the cutting inserts take a flatter, shallower cut and thus the maximum force of impact is less than is the case with conventional milling cutters.
Further in accordance with the invention, power means are provided for feeding the milling head toward and away from the camshaft in order to mill the desired cam profile, with signal means for determining the rotative position of the camshaft and for producing, processing and transmitting a signal based on that determination to operate the power means. Also a power drive is provided for variably rotating the camshaft so as to maintain a constant surface speed of the cam as it is milled to the desired contour, with signal means for determining the position of the milling head in relation to the camshaft and for producing, processing and transmitting a signal based on that determination to operate the power drive. The signal means for determining the rotative position of the camshaft and the position of the milling head in relation to the camshaft each includes a position transducer and a computer.
These and other objects of the invention will become more apparent as the following description proceeds especially when considered with the accompanying drawings.